Gyratory crushers are used for crushing ore, mineral and rock material to smaller sizes. Typically, the crusher comprises a crushing head mounted upon an elongate main shaft. A first crushing shell (typically referred to as a mantle) is mounted on the crushing head and a second crushing shell (typically referred to as a concave) is mounted on a frame such that the first and second crushing shells define together a crushing chamber through which the material to be crushed is passed. A driving device positioned at a lower region of the main shaft is configured to rotate an eccentric assembly positioned about the shaft to cause the crushing head to perform a gyratory pendulum movement and crush the material introduced in the crushing chamber. Example gyratory crushers are described in WO 2008/140375, WO 2010/123431, US 2009/0008489, GB 1570015, U.S. Pat. No. 6,536,693, JP 2004-136252, U.S. Pat. No. 1,791,584 and WO 2012/005651.
Primary crushers are heavy-duty machines designed to process large material sizes of the order of one meter. Secondary and tertiary crushers are however intended to process relatively smaller feed materials typically of a size less than 35 centimeters. Cone crushers represent a sub-category of gyratory crushers and may be utilised as downstream crushers due to their high reduction ratios and low wear rates.
Typically, a spacer (or filler) ring is used to accommodate different geometries of different concaves and in particular to adapt the same topshell for mounting medium or fine sized concaves used in secondary and tertiary crushers in contrast to the much larger diameter coarse concaves that fit directly against the topshell and have a maximum diameter to receive large objects for crushing. WO 2004/110626 discloses a gyratory crusher topshell having a plurality of different spacer ring embodiments for mounting a variety of different concaves at the crushing region.
Conventionally, the spacer ring comprises a radially outward facing cylindrical surface for mating against a corresponding inward facing cylindrical surface of the topshell. A form of anchorage is therefore required to axially lock the spacer ring at the topshell without which the spacer ring would be pushed axially upward by the crushing force imparted by the outer crushing shell during use. WO 2004/110626 describes the use of anchorage bolts that extend through a radially outward projecting flange of the spacer ring to be secured within a grooved region located at the upper rim of the topshell wall. These anchorage bolts are also configured to provide a radial lock for the spacer ring at the topshell without which the ring would rotate around the longitudinal axis due to the gyroscopic precession of the crushing head within the crushing chamber.
However, a spacer ring having an outwardly projecting flange can be difficult to install within the topshell due to the required closeness of fit. Additionally, due to the significant torque forces resultant from the crushing action, it is a common problem that these conventional mechanisms for axial and rotational locking of the spacer ring fail following only short or moderate usage. Accordingly, what is required is a topshell assembly that addresses these problems.